Proper prop for 21 zodiac w twin f70

[Nicturner]

Trying to figure out the proper props for my zodiac 21 open pro with twin F70's at full speed barely hits 4500 rpms and only and is sluggish. I currently have 17 pitch and think I should go way down, but don't want to go to low. Any recommendations? I used the wizard on the Yamaha sight but they don't have any inflatable options.
Thanks in advance

[Jason2tpa]

What is the spec rpm range @ WOT for your engine?
Is your 21" SS or AL, 3 or 4 blade?

You want to reach top end of spec rpm range @ WOT. When guesstimating what pitch prop to choose, the rule of thumb is for every inch of pitch = 150-200 rpms.

If your zodiac is 21' and v-hull I recon it's dry hull weight is over 1,000lbs. In which case, when using the yamaha prop selector choose a standard fiberglass hull similar to yours.

[Nicturner]

Currently have alum 3 blade on both and only hits 4500 rpms. Wot is 6300 for f70. It's dry wieght is somewhere under 2000 lbs with gas and load

[Nicturner]

It says I should 14 diameter and 11 pitch. Seems like drastic change?

[99yam40]

See if you can find rigs similar to yours with twins on the Yamaha Performance Bulletins to see what they used

Or try a forum on Zodiacs

Outboard Performance, Performance Bulletins | Yamaha Outboards